Research Of Blockage Detection In Oil Pipeline Based On Auto-oscillations Theory

In recent years, pipeline transportation has become the main way of fluid transportation. And the transportation market has been dominated by long-distance oil pipeline. But after using the pipeline for a long time, there will be a series of problems, such as paraffin wax, microbial corrosion, and valve failure, which can cause pipe blockage. It will affect the normal working condition of the pipeline. As a result, the crude oil in the pipeline will leakage, and pipeline even burst. Oil leakage can not only pollute the environment, but also cause great waste of valuable resources. And, pipeline burst also threaten the safety of people’s lives and property. In addition, pipeline blockage also decreases the quality of oil products. When the pipeline is blocked, the basis of solving pipeline blockage is to locate the blockage and the quantity of the blockage. Therefore, it is urgent to find a method that is both accurate and applicable.This research uses auto-oscillations theory to study the plugging problem. First, the pipeline mathematical model is established. Then, the water level changes of the tank and instant off valve are chosen as the incentive, and two points in two different locations in the pipeline will be detected. Then the incentives response characteristic curve of the pipeline is analyzed. So the blocking point and blocking quantity can be acquired.In the application of fluid auto-oscillations theory, water hammer control equation of fluid motion in the oil pipeline including the variable of blocking point position is proposed. And Dirac delta function is introduced to deal with the equation, then express it. Under the fixed boundary condition, the analytic solution of the equation is obtained and express with Fourier series method. Finally, the analytic solution of the equation with Fourier series is analyzed. The amplitude of each composition component harmonic waves under different cycle can be obtained. According to the amplitude of different harmonic waves in different periods, the plug attenuation parameter of every harmonic wave will be known. The blocking position can be identified by the ratios of two separate composition component harmonic waves, and then the magnitude in water-supply pipelines can be further identified by plug attenuation parameter value of each separate composition component harmonic waves accurately.By using the experimental platform of the pipeline system, the pipe plug is replaced with the valve which is not completely opened. And, instant off valve is chosen to generate incentives and then measure arbitrary point’s pressure response characteristic. Then, the data from experiments is used to validate the correctness of the detecting method proposed in this paper.In this paper, the auto-oscillations theory and a pressurized fluid transient theory have been associated. Fourier series analysis and the plug attenuation parameter are employed to detect oil pipeline jams. The method has high accuracy and short calculation time in determining the blockage location and magnitude in oil-supply pipelines. And, the practical application range is wide. Therefore, this method has practical referencing value for blockage detection in practical oil-supply pipelines.